Someone asked me, how to make an object become invisible in Live Mode and visible again in Build/Buy Mode. Good for OMSPs, kind of like my Invisible Kitchen Surface.

This tutorial is for a non-recolorable object, or an object whose recolor doesn't matter to you. It'll just change material based on whether you're in Live Mode or not and ignore the recolor chosen by design tool.

You'll need SimPE and some basic knowledge of it.

Create an invisible material

• clone an existing TXMT
• on cMaterialDefinition tab, rename the material in Description field to something resembling invisibility
• copy-paste the new name to Filename field adding _txmt at the end
• change Type to Null
• fix TGI and Commit

Add both visible and invisible material names to text list #88

• create this resource, if there isn't one in your package already:
  
  • clone an existing text list, i.e. Model Names
    
  • change its instance number from 85 to 88
    
  • change its filename to Material Names or something like that
    
  • remove model names or whatever text was written there
• copy-paste your visible and invisible material names to any two lines
• if the TXMT is custom, i.e. created by you, add ##0x1C050000! in front of the name
• if the TXMT is an in-game resource, don't add ##0x1C050000! (like maybe you're editing a Maxis object and using its original material for the visible state)
• Commit File

Add the subset name you want to become invisible to text list #87

• create this resource, if there isn't one in your package already:
  
  • clone an existing text list, i.e. Model Names
    
  • change its instance number from 85 to 87
    
  • change its filename to Subset Names or something like that
    
  • remove model names or whatever text was written there
• write the subset name to any line (find it in GMDC -> Groups)
• Commit File

Create a BHAV named Function - Stop Live Mode

• clone an existing BHAV, i.e. Function - Init
• change its instance number to a number that hasn't been used yet (say, there are BHAVs from 1000 to 1006 in your package, then use 1007)
• change Filename to: Function - Stop Live Mode
• delete all lines (Special Buttons -> Delete to end), it won't let you delete line 0, that's ok
• select line 0
  
  • change OpCode to 2
    
  • open raw entry box by clicking a quotes button
    
  • if your object is 1-tile, copy-paste this: 00000B0000050A030000000000000000
    
  • if your object is multi-tile, copy-paste this: 0000130000050A030000000000000000
    
  • you should see: Expression (Stack Object ID := My object id) or Expression (Stack Object ID := My lead tile object ID)
    
  • change True Target to 1
    
  • change False Target to Error (using drop-down list)
• add a line (click Add)
• select the new line 1
  
  • change OpCode to 6D
    
  • click an X button to set all operands to zero
    
  • copy-paste this to raw entry box: 00000000000A00000A00000000000000
    
  • you should see: Change Material (Stack Object ID, Me ("something"), Me ("something"))
    
  • open a wizard by clicking a wrench and axe button
    
  • make sure you see the visible material name and the subset you want to toggle (if material name is long, place your cursor on it and click keyboard right arrow to go to the end)
    
  • if material or subset is wrong, change index number until you see the right one (don't click fast forward buttons, they don't work)
    
  • change True Target to Return True (using drop-down list)
    
  • change False Target to also Return True
• Commit File

Create a BHAV named Function - Start Live Mode

• clone the Stop Live Mode BHAV you've just finished
• change its instance number to an unused number (if there are BHAVs from 1000 to 1007 in your package, use 1008)
• change Filename to: Function - Start Live Mode
• select line 1
  
  • open a wizard
    
  • change material index number to the invisible one
• Commit File

Add the new functions to OBJf

• open the OBJf, there's probalby at least one in your package
• select Start Live Mode
• click a play/triangle button next to Action BHAV field
• choose your Function - Start Live Mode
• Okay it and make sure it appeared in the Action BHAV field
• select Stop Live Mode and do the same for Function - Stop Live Mode
• Commit File
• if your object is multi-tile and has more OBJfs, you may have to do the same for them (actually, you might have to do it only for the lead tile's OBJf and leave the rest alone, but I'm not sure and I don't feel like testing, if you do it, tell me the results please :D)

Notes
In apartments, this method causes the object in hidden unit to show itself when not in Live Mode. If it bothers you, you could add checks for that to BHAVs.

For recolorable objects, if you want the game to respect the recolor chosen by design tool, it's a bit more complicated. You can do it the way clean and dirty material states are done, with additional MMATs and TXMTs and the right naming and flags and stuff. There's probably a tutorial somewhere on how to do clean and dirty states, just consider clean state as visible and dirty state as invisible. Basically, you'll have to add a dirty TXMT and MMAT to every recolor and rename all of them. The correct naming is important in this case. If your object already has clean and dirty states and you want to keep them, there's an option to use lit and unlit states for this purpose, but I haven't tried it. It'll probably multiply the amount of TXMTs and MMATs like crazy, if it even works. I don't recall any objects that have lit/unlit as well as clean/dirty states, it might not be doable.

Thank you for the tutorial! I have used it to edit these OMSPs. I did have to do a couple of tweaks and I wonder whether this is an issue with the object or because I did something else wrong.
--> In the txt list materials name I had to put them in a certain order: first the invisible txmt and then the original txmt
--> I've added an extra line in the BHAV between stack object and change material: stack object's graphic: literal 0x0002 (removing this line did not fix the issue with the txmts having to be in that specific order)

Hi @Klaartje

As long as you point to the right material name in the Change Material primitive in the BHAV, the order in which they are listed in the text list doesn't matter. It's not wrong to have them the way you have them, if it's easier for you. (In some cases, MMATs also look into the list and you have to point them to the right lines, but not in this case.)

Your objects only have one model/graphic, so adding a graphic change is not what I would do. You're basically telling it to display a second model when it doesn't exist. Doesn't it give you errors? Maybe the game ignores it. Is there something you were trying to achieve with it?

@Lamare Thanks for your quick reply! Following your tutorial doesn't turn the object invisible in live mode, the material didn't change at all. That's why I started poking at it and trying different things. I think the extra line came from your invisible counter. Now that I've looked at it a bit more, it doesn't give me any errors because that particular line in model names is empty. So I can just remove it.

The order of the materials still matters, if I reverse them (and fix the lines in the BHAVs so they correspond) it stops turning invisible.

Weird. Maybe there really is something special about your objects. I bet on MMAT or some kind of texture reset. Being recolorable and having an MMAT shouldn't be a problem in itself, I tested SilentLucidity's OMSP for this tutorial, and it is recolorable, and the order of materials does not matter. Attaching the file in case you're interested in poking around in it. Although, you managed to make it work, right? The rest is history :D